The Question:

“Dear Scientist,

I have noticed birds on Whitshed Road in the spring in years past. Do you know when those birds arrive, how long they are here, and why they spend so much time on the road?”
– Sincerely, a curious Cordovan

The Answer:

What an important question to ask this time of year! To answer it, I contacted Milo Burcham, a retired USFS biologist and vice president of Prince William Sound Audubon.

The springtime northerly migration of birds has begun! While we here in Cordova like to focus on the shorebird migration, many other species are also moving from their wintering grounds to their breeding grounds. Some might spend winters as far away as Antarctica (Arctic Terns), the southern tip of South America (Hudsonian Godwits and Red Knots), Central and South America (most Warblers, Thrushes, Flycatchers), and parts of the lower 48 States (many Sparrows, Kinglets, Hummingbirds). They are heading to breeding grounds throughout Alaska, including right here on the Copper River Delta to as far as the Bering Sea and Arctic Coasts! That’s a lot of flying, and it takes a lot of energy.

While birds are well adapted to these migrations, certain conditions can make it more difficult. Last spring, we saw a large number of birds appear overnight. We suddenly saw them in our yards, grassy fields, and on our roads. What we witnessed was a migration fallout. This is when certain weather conditions, such as strong, unfavorable winds, make migration much more difficult than usual, resulting in large numbers “dropping out” to rest and refuel.

We witnessed large numbers of Golden-crowned Sparrows, Hermit Thrushes, American Robins, Varied Thrushes, and others suddenly appearing in our yards and lining our roadways. These birds were exhausted and vulnerable to starvation, predation, and being hit by cars. Vehicle collisions take an estimated 214 million birds each year. So, what can we do if we see such an event again? First of all, slow down while driving our roadways. Many birds were killed by cars last year, especially along the Whitshed Road. Reducing our speed can save the lives of many birds if we start to see them along our roads.

There are a few other things we can do to help birds. The single largest source of human-caused bird mortality in North America is cats! This includes both feral cats and pet cats that are allowed to go outside. These cats kill an estimated 2.4 BILLION birds each year! Keeping your cat indoors, especially during migration season, can save the lives of many birds. Window strikes are the next most common cause of human-caused bird mortality and result in annual deaths of almost 600 million birds. Placing a grid of stickers on the outside of windows can significantly reduce these deaths.

Milo encourages all of us to get out there and enjoy the sights and sounds of our local birds. “We are more likely to want to conserve what we see and understand,” stated Milo. Thanks to Milo Burcham for his help answering this question. We are currently seeking out more Ask a Scientist questions. Whether you are out in the Sound or out the road, if you observe something strange and have a question about what is going on please email it to creo@pwssc.org.